Most modern automotive fuel systems utilize fuel injectors to provide precise metering of fuel for introduction towards each combustion chamber. Additionally, the fuel injector atomizes the fuel during injection, breaking the fuel into a large number of very small particles, increasing the surface area of the fuel being injected, and allowing the oxidizer, typically ambient air, to more thoroughly mix with the fuel prior to combustion. The metering and atomization of the fuel reduces combustion emissions and increases the fuel efficiency of the engine. Thus, as a general rule, the greater the precision in metering and targeting of the fuel and the greater the atomization of the fuel, the lower the emissions with greater fuel efficiency.
An electro-magnetic fuel injector typically utilizes a solenoid assembly to supply an actuating force to a fuel metering assembly. Typically, the fuel metering assembly is a plunger-style closure member which reciprocates between a closed position, where the closure member is seated in a seat to prevent fuel from escaping through a metering orifice into the combustion chamber, and an open position, where the closure member is lifted from the seat, allowing fuel to discharge through the metering orifice for introduction into the combustion chamber.
The fuel injector is typically mounted upstream of the intake valve in the intake manifold or proximate a cylinder head. As the intake valve opens on an intake port of the cylinder, fuel is sprayed towards the intake port. In one situation, it may be desirable to target the fuel spray at the intake valve head or stem while in another situation, it may be desirable to target the fuel spray at the intake port instead of at the intake valve. In both situations, the targeting of the fuel spray can be affected by the spray or cone pattern. Where the cone pattern has a large divergent cone shape, the fuel sprayed may impact on a surface of the intake port rather than towards its intended target. Conversely, where the cone pattern has a narrow divergence, the fuel may not atomize and may even recombine into a liquid stream. In either case, incomplete combustion may result, leading to an increase in undesirable exhaust emissions.
Complicating the requirements for targeting and spray pattern is cylinder head configuration, intake geometry and intake port specific to each engine's design. As a result, a fuel injector designed for a specified cone pattern and targeting of the fuel spray may work extremely well in one type of engine configuration but may present emissions and driveability issues upon installation in a different type of engine configuration. Additionally, as more and more vehicles are produced using various configurations of engines (for example: inline-4, inline-6, V-6, V-8, V-12, W-8 etc.,), emission standards have become stricter, leading to tighter metering, spray targeting and spray or cone pattern requirements of the fuel injector for each engine configuration.
It has been determined that a fuel spray pattern using a circularly arrayed and non-angled metering orifices can lead to a somewhat uneven flow pattern, which can be seen by injecting fuel onto a target area transverse to the longitudinal axis and spaced at a predetermined distance from the fuel injector. That is to say, even though the circular array of metering orifices of such an injector should provide a hypothetically circular and symmetrical flow pattern on the target transverse area, the fuel injector fails to do so due to an interplay between respective concentricities of the array of non-angled metering orifices, a seat orifice of the injector and the longitudinal axis. And in some cases, more fuel is actually delivered to different areas of the hypothetical circular flow area, leading to a formation of “lobes” formed within the hypothetical circular flow area. The formation of lobes in the flow area tends to require costly adjustments to a fuel injector and its mounting arrangement or even specially configured fuel injector that may or may not compensate for the uneven fuel distribution about the hypothetical circular area on the lobes.
It is believed that known metering orifices formed at an angle with respect to a longitudinal axis (i.e., “angled metering orifices”) of a fuel injector and arrayed in circular pattern along the longitudinal axis allow greater symmetry and greater latitude in configuring the fuel injector to operate with different engine configuration while achieving an acceptable level of fuel atomization, (quantifiable as an average Sauter-Mean-Diameter (SMD)). It is believed, however, that angled metering orifices require, at the present time, specialized machinery, trained operators and greater inefficiencies to manufacture than non-angled metering orifices.
It would be beneficial to develop a fuel injector in which non-angled metering orifices can be used in controlling spray targeting and spray distribution of fuel. It would also be beneficial to develop a fuel injector in which increased atomization or precise targeting can be changed so as to meet a particular fuel targeting and cone pattern from one type of engine configuration to another type. Furthermore, it would be beneficial to develop a fuel injector in which a circular array of non-angled metering orifices provides a flow area with a plurality of uniform radii about the longitudinal axis on a transverse plane without requiring specialized adjustments or configuration of the fuel injector in order to deliver a symmetrical circular flow area pattern.